1. Field of the Invention
The present invention relates to a linear motion guide device, and more particularly to a linear motion guide device having two offset rows of balls.
2. Description of the Prior Art
Typical machine devices may include one or more bearing devices or linear motion guide devices engaged between the machine elements for facilitating the moving or the sliding between the machine elements. U.S. Pat. No. 5,947,605 to Shirai discloses one of the typical linear motion guide apparatuses equipped with a plurality of rows of ball chains. However, the typical linear motion guide devices may not be used in the heavy duty machine devices for resisting the great forces or torques that may be transmitted between the machine elements of the machine devices. The ball row chain includes a number of spacer members secured together on or along a single connection member. The spacer members may not stably hold the balls in place such that the balls may be easily disengaged from the spacer members. In addition, the balls may be forced to act onto the spacer members while the balls and the ball row chain are rotated or turned relative to the machine parts.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional linear motion guide devices for machine members.
The primary objective of the present invention is to provide a linear motion guide device including two offset rows of balls for resisting the great forces or torques that may be transmitted between the machine elements of the machine devices.
The other objective of the present invention is to provide a linear motion guide device including two offset rows of balls for being stably and solidly secured between the machine elements of the machine devices.
In accordance with one aspect of the invention, there is provided a linear motion guide device comprising an endless ball chain including two rows of openings formed therein and offset from each other, and including a plurality of spaces provided between the openings thereof, and two rows of balls engaged in the openings of the endless ball chain and engaged between the spacers and offset from each other. The offset of the two rows of balls allows the two rows of balls to be moved, one by one, across the turning portion between two machine elements.
The spacers each includes at least one notch formed therein for increasing a deformability of the spacers. The formation or the provision of the notches in the spacers may increase the deformability of the spacers, particularly when the spacers are squeezed by the balls and/or by the machine elements. The grease or the lubrication oil may be suitably retained between the balls that are offset from each other.
The endless ball chain includes two side flanges and an intermediate flap, the spacers are formed between the side flanges and the intermediate flap of the endless ball chain.